怎样动态操作js/css文件

 <script language="JavaScript">
//动态加载一个js/css文件
function loadjscssfile(filename, filetype){
if (filetype=="js"){
varfileref=document.createElement('script')
fileref.setAttribute("type","text/javascript")
fileref.setAttribute("src",filename)
}
else if (filetype=="css"){
varfileref=document.createElement("link")
fileref.setAttribute("rel","stylesheet")
fileref.setAttribute("type","text/css")
fileref.setAttribute("href",filename)
}
if (typeof fileref!="undefined")
document.getElementsByTagName("head")[0].appendChild(fileref)
}
</script>

loadjscssfile("myscript.js","js")
loadjscssfile("javascript.PHP","js")
loadjscssfile("mystyle.css","css")
<scriptlanguage="javascript">
//移动已经加载过的js/css
function removejscssfile(filename,filetype){
vartargetelement=(filetype=="js")? "script" :(filetype=="css")? "link" : "none"
var targetattr=(filetype=="js")?"src" : (filetype=="css")? "href" :"none"
varallsuspects=document.getElementsByTagName(targetelement)
for (var i=allsuspects.length; i>=0;i--){
if (allsuspects[i] &&allsuspects[i].getAttribute(targetattr)!=null && allsuspects[i].getAttribute(targetattr).indexOf(filename)!=-1)
 allsuspects[i].parentNode.removeChild(allsuspects[i])
}
}
</script>

removejscssfile("somescript.js","js")
removejscssfile("somestyle.css","css")